US007215653B2
`
`(12) United States Patent
`Kim et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7.215,653 B2
`May 8, 2007
`
`(54) CONTROLLING DATA TRANSMISSION
`RATE ON THE REVERSE LINK FOR EACH
`MOBILE STATION IN ADEDICATED
`MANNER
`
`(75) Inventors: Ki Jun Kim, Seoul (KR); Young Cho
`Kim, Seoul (KR); Young Jo Lee,
`Kunpo (KR); Jong Hoe An, Anyang
`(KR); Young Woo Yun, Seoul (KR):
`Young Jun Kim, Anyang (KR)
`
`(73) Assignee: LG Electronics Inc., Seoul (KR)
`(*) Notice:
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 962 days.
`(21) Appl. No.: 10/071,243
`
`(22) Filed:
`
`Feb. 11, 2002
`
`(65)
`
`Prior Publication Data
`US 20O2/O141349 A1
`Oct. 3, 2002
`
`Foreign Application Priority Data
`(30)
`Feb. 12, 2001
`(KR) ...................... 10-2001-OOO6839
`Jul. 10, 2001
`(KR) ...................... 10-2001-0041363
`Sep. 18, 2001
`(KR) ...................... 10-2001-00576OO
`
`(51) Int. Cl.
`(2006.01)
`H04O 700
`(52) U.S. Cl. ........................ 370/329; 370/332:455/68;
`455/69
`(58) Field of Classification Search ..................... None
`See application file for complete search history.
`References Cited
`
`(56)
`
`U.S. PATENT DOCUMENTS
`
`5/2000 EZak et al. ................ 370,335
`6,069,883. A *
`6,389,034 B1*
`5/2002 Guo et al. .....
`... 370,441
`6,411,799 B1* 6/2002 Padovani ..........
`6,741,862 B2 *
`5/2004 Chung et al. ............ 455,452.1
`6,996,127 B2 * 2/2006 Rezaiifar et al. ........... 370/468
`
`- - - - - - - - 455.69
`
`FOREIGN PATENT DOCUMENTS
`
`EP
`EP
`EP
`EP
`GB
`WO
`WO
`
`4f1997
`O 767 548 A2
`5, 2000
`1 003 302 A2
`1, 2001
`1 067 729 A2
`1067729
`* 1?2OO1
`2269296 A * 2, 1994
`WO 98.24199
`6, 1998
`WOOOf 14900
`* 3f2OOO
`
`* cited by examiner
`Primary Examiner Huy D. Vu
`Assistant Examiner—Robert W. Wilson
`(74) Attorney, Agent, or Firm—Fleshner & Kim, LLP
`(57)
`ABSTRACT
`
`The data transmission rate on the reverse link in a mobile
`communications system is controlled by determining an
`interference level at a base station due to signals from all
`mobile stations served by the base station, and determining
`a transmission energy level required for each mobile station.
`The interference level is compared with the transmission
`energy level to obtain a comparison result for each mobile
`station, and each mobile adjusts its data transmission rate
`based upon the comparison result, which is sent via a
`common channel on a forward link to each mobile station in
`a dedicated manner. Thereafter, packet data is transmitted on
`the reverse link in accordance with the adjusting so that data
`throughput can be maximized.
`
`5,603,096 A * 2/1997 Gilhousen et al. ............ 455/69
`
`40 Claims, 8 Drawing Sheets
`
`A.
`
`RECEPTION
`PROCESSOR
`
`
`
`
`
`
`
`
`
`TRANSMISSION DATA
`RATE CONTROLLER
`
`TRANSMSSION DATA
`CONTROL COMMAND
`
`TRANSMISSION
`PROCESSOR
`
`
`
`Ex. 1001 - Sierra Wireless, Inc.
`Sierra Wireless, Inc., et al. v. Sisvel S.P.A., IPR2021-01141
`Page 1 of 19
`
`

`

`U.S. Patent
`
`May 8, 2007
`
`Sheet 1 of 8
`
`US 7.215,653 B2
`
`F. G. 1
`PRIOR ART
`
`10
`
`
`
`BIT REPETITION
`
`
`
`RAB
`
`11
`
`WALSH COVER
`
`SIGNAL POINT MAPPNG
`O => +1
`1 => -1
`
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`
`

`

`U.S. Patent
`
`May 8, 2007
`
`Sheet 2 of 8
`
`US 7.215,653 B2
`
`
`
`RECEPTION
`PROCESSOR
`
`
`
`
`
`COMPARATOR
`E
`INTERFERENCE
`LEVEL, DETECTOR (YES f
`
`A4
`
`TRANSMISSION
`PROCESSOR
`
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`

`

`U.S. Patent
`
`May 8, 2007
`
`Sheet 3 of 8
`
`US 7.215,653 B2
`
`FG. 4
`
`RATE-CONTROL BITS
`FOR USER O (ORN)
`(1 B f 20 MS)
`
`n=16 FF N=12
`=8 F N=24
`=4 F N=48
`n=2 FN-96
`-
`-
`in
`n=1 F N=192
`
`FEETO
`
`41
`
`
`
`SYMBO f 1 SLOT F N=12
`SYMBO
`2 SLOTS F N=24
`SYMEO ( 4 SLOTS EF N=48
`AR DATA BATE -
`NITIAL OFFSE VALUES
`1 SYMBOL | 8 SLOTS IFN-96
`a; SYMBOL | 16 SLOTS IF N=192 ASSIGNED TO EACH USER OF
`43
`44 1.2 KBPS F N=24
`2.4 KBPS F N=48
`4.8 KBPS F Ne96
`9.6 KBPS F N=192
`
`CNEL
`
`SGNAL POINT MAPPNG
`O- +1,
`1---
`NO SYMBOL -- 0
`
`MUX
`
`X
`
`:
`
`RATE-CONTRO BITS
`FOR USER N-1 (CR 2N-1)
`(1 BiT 20 MS)
`
`FEFTOR
`
`N IS THE NUMBER OF
`USERS NEACH ARM
`
`LONG CODE MASK
`
`CNEL
`
`sign,ON: up NG
`NO SYMEOL-- 0
`45
`T46 T47TT 48
`LONG CODE
`RELATIVE
`OFFSET
`GENERATOR
`CALCULATION
`(1.2288 MCPS)
`
`DECIMATOR
`
`RATE-CONTROL BITS
`FOR USER O (ORN)
`(1 BIT f 20 MS)
`
`REPEATOR
`nX
`
`SIGNAL POINT MAPPNG
`O -- +1,
`1 - -
`NC SYBO -- O
`
`
`
`
`
`MUX
`
`RATE-CONTROL BITS
`FOR USER N-1 (OR 2N-1)
`(1 BT 20 MS)
`
`REPEATOR
`
`-- -1
`O - +1,
`NO SYMBOL-- 0
`
`CHANNEL
`GAN
`
`1 SYMBOL ( 1 SLOT IF N=12
`1 SYMBOL f 2 SLOTS F N-24
`1 SYMBOL f 4 SLOTS F N=48
`1 SYMBOL / 8 SLOTS F N=96
`1 SYMBOL / 16 SOTS F N=192
`
`NITAL OFFSET VALUES
`ASSIGNED TO EACH USER
`
`Q-ARDAA RATE =
`0.6 KBPS F N-12
`12 KBPS F N=24
`4 KBPS F N=48
`4.8 KBPS FN-96
`96 KBPS F N=192
`
`Ex. 1001 - Sierra Wireless, Inc.
`Sierra Wireless, Inc., et al. v. Sisvel S.P.A., IPR2021-01141
`Page 4 of 19
`
`

`

`U.S. Patent
`
`May 8, 2007
`
`Sheet 4 of 8
`
`US 7.215,653 B2
`
`F.G. 5
`
`S51
`
`S52
`
`BS DETERMINES INTERFERENCE LEVEL
`OF ALL TRAFFIC CHANNELS
`
`
`
`
`
`COMPARE INTERFERENCE LEVEL
`WITH THRESHOLD WALUE
`
`DETERMINE REVERSE LINK LOAD
`
`DETERMINE DATA TRANSMISSION RATE ADJUSTMENT
`AND TRANSMISSION CHANNEL FOR EACH MS
`BASED ON REVERSE NK LOAD AND
`DISTANCE BETWEEN MS AND BS
`
`S54
`
`
`
`TRANSMIT TO MS
`
`S55
`
`
`
`
`
`
`
`
`
`Ex. 1001 - Sierra Wireless, Inc.
`Sierra Wireless, Inc., et al. v. Sisvel S.P.A., IPR2021-01141
`Page 5 of 19
`
`

`

`U.S. Patent
`
`May 8, 2007
`
`Sheet 5 of 8
`
`US 7.215,653 B2
`
`F.G. 6
`
`DETERMNE INTERFERENCE LEVELAT BS
`DUE TO S GNAES FROM MS
`
`DETERMINE TRANSMISSION ENERGY LEVEL
`REQUIRED FOR EACH MS
`
`S60
`
`S62
`
`
`
`COMPARE INTERFERENCE LEVEL WITH TRANSMISSION ENERGY LEVEL
`TO OBTAN A COMPARISON RESULT FOR EACH MS
`
`S64
`
`SEND COMPARISON RESULT WA A COMMON CHANNEL
`ON A FORWARD LNK TO EACH MS IN A DEDICATED MANNER
`
`ADJUST DATA TRANSMISSION RATE FOR EACH MS
`BASED UPON THE COMPARISON RESULT
`
`S66
`
`S68
`
`TRANSMIT PACKE DATA ON REVERSE LINK
`
`-$69
`
`Ex. 1001 - Sierra Wireless, Inc.
`Sierra Wireless, Inc., et al. v. Sisvel S.P.A., IPR2021-01141
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`
`

`

`U.S. Patent
`
`May 8, 2007
`
`Sheet 6 of 8
`
`US 7.215,653 B2
`
`F. G. 7
`
`BS
`CALCULATE MS PRI
`OR RECEIVE FROM MS
`
`CALCULATE MS RCW
`
`DETERMINE TOTAL INTERFERENCE
`RECEIVED ATBS
`
`GENERATE RCB FOR EACH MS
`USING MS RCW AND MS TAB
`
`S70
`
`S71
`
`S72
`
`S74
`
`MS
`
`TRANSMIT MSAB
`
`S73
`
`TRANSMT RCB TO EACH MS
`
`
`
`RECEIVE RCB FROM ALL ACTIVE BS
`
`S
`76
`
`GENERATE COMBINED RCB TO CONTROL
`REVERSE LINK DATA RATE
`
`S77
`
`Ex. 1001 - Sierra Wireless, Inc.
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`Page 7 of 19
`
`

`

`U.S. Patent
`
`May 8, 2007
`
`Sheet 7 of 8
`
`US 7,215,653 B2
`
`FG. 8
`
`TOTAL INTERFERENCE
`(ROT)
`
`
`
`BS RCW = BS RCW - A2
`
`UNCHANGED
`
`BS RCW = BS RCV + A
`
`FG 9
`
`
`
`COMPARE MS RCW, BS RCW,
`MS AB CONDITIONS
`MS RCW +A< BS RCW
`&
`MS AB = INCREASE
`
`
`
`MS RCV > BS RCW
`
`NCREASE
`
`UNCHANGED
`
`DECREASE
`
`S33
`
`Ex. 1001 - Sierra Wireless, Inc.
`Sierra Wireless, Inc., et al. v. Sisvel S.P.A., IPR2021-01141
`Page 8 of 19
`
`

`

`U.S. Patent
`
`May 8, 2007
`
`Sheet 8 of 8
`
`US 7,215,653 B2
`
`BS
`CALCULATE MS PR
`OR RECEIVE FROM MS
`
`CALCULATE MS RCW
`
`DETERMINE TOTAL INTERFERENCE
`RECEIVED ATBS
`
`UPDATE BS RCV ACCORDING TO
`TOTAL INTERFERENCE (ROT)
`
`GENERATE RCB FOR EACH MS
`USING MS RCW AND MS AB
`
`TRANSMT RCB TO EACH MS
`
`FIG 10
`
`S100
`
`S102
`
`S104
`
`S106
`
`S110
`
`O
`
`S112
`
`MS
`
`TRANSMT MS AB
`-
`
`RECEIVE RCB FROM
`ALL ACTIVE BS
`
`GENERATE COMBINED RCB TO
`CONTROL REVERSE LINK DATA RATE
`
`S108
`
`S114
`
`S116
`
`Ex. 1001 - Sierra Wireless, Inc.
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`Page 9 of 19
`
`

`

`US 7,215,653 B2
`
`1.
`CONTROLLING DATA TRANSMISSION
`RATE ON THE REVERSE LINK FOR EACH
`MOBILE STATION IN ADEDICATED
`MANNER
`
`2
`not described in detail herein, are also part of the present
`invention. For example, specific details of the protocol
`architecture having an air interface with a layered structure,
`physical layer channels, protocol negotiation and process
`ing, and the like have been omitted.
`In a communications system, a set of “channels' allow
`signals to be transmitted between the access network (e.g.,
`a base station) and the access terminal (e.g., a mobile) within
`a given frequency assignment. Channels consist of “forward
`channels' and “reverse channels.”
`Signal transmissions (data transmissions or transfers)
`from the base station to a mobile via a downlink (i.e.,
`forward channels) are commonly referred to as the “forward
`link,' while signal transmissions from the mobile to the base
`station via an uplink (i.e., reverse channels) are commonly
`referred to as the “reverse link.”
`So-called “physical layers' provide the channel structure,
`frequency, power output, modulation, and encoding speci
`fications for the forward and reverse links. The “forward
`channels' consist of those physical layer channels transmit
`ted from the access network to the access terminal, and
`“reverse channels' consist of those physical layer channels
`transmitted from the access terminal to the access network.
`Of the many portions of the forward and reverse channels,
`the “forward MAC channel’ is the portion of the forward
`channel dedicated to medium access control (MAC) activi
`ties. The forward MAC channel consists of the reverse
`power control (RPC) channel, the reverse activity (RA)
`channel, and other channels. Here, the forward MAC reverse
`activity (RA) channel indicates the activity level (e.g., the
`load) on the reverse channel.
`In the so-called Interim Standard 95A (IS-95A) systems,
`the forward link and the reverse link are allocated separate
`frequencies and are independent of one another. For code
`division multiple access (CDMA) technology is the basis for
`Interim Standard 95 (IS-95) and can operate in both the
`800-MHz and 1900-MHz frequency bands. In CDMA sys
`tems, communications between users are conducted through
`one or more cells/sectors, which are serviced by base
`stations. A user of a first mobile communicates with another
`user on a second mobile by transmitting voice and/or data on
`the reverse link to a cell/sector. The cell/sector receives the
`data for routing to another cell/sector or a public switched
`telephone network (PSTN). If the second user is on a remote
`station, the data is transmitted on the forward link of the
`same cell/sector, or a second cell/sector, to the second
`remote station. Otherwise, the data is routed through the
`PSTN to the second user on the standard phone system.
`A mobile communications system can employ connec
`tionless network services in which the network routes each
`data packet individually, based on the destination address
`carried in the packet and knowledge of current network
`topology. The packetized nature of the data transmissions
`from a mobile allows many users to share a common
`channel, accessing the channel only when they have data to
`send and otherwise leaving it available to other users. The
`multiple access nature of the mobile communications system
`makes it possible to provide Substantial coverage to many
`users simultaneously with the installation of only one base
`station in a given sector.
`The transfer of digital data packets differs from the
`transfer of digital voice information. Full duplex (simulta
`neous two-way) Voice communication patterns imply that
`the data, transferred between the base station and a particular
`mobile station, are real-time and Substantially equal in
`bandwidth. It has been noted that a total delay of 200 msec
`(about 2. Kbits of digital data for most speech vocoders)
`
`FIELD OF THE INVENTION
`
`The present invention generally relates to mobile (or
`wireless) communications, and in particular, to controlling
`data transmission (transfer) rates between a base station and
`mobile stations served by the base station so that data
`throughput is advantageously increased.
`
`10
`
`BACKGROUND OF THE INVENTION
`
`15
`
`Mobile communications involve, among various process
`ing procedures, signal transmissions and handling of data
`traffic between an access network (AN) and an access
`terminal (AT). An access network (AN) comprises many
`elements, one of which being a base station, as known by
`those skilled in the art. An access terminal (AT) can be in
`many forms, including a mobile station (e.g., a mobile
`phone), a mobile terminal (e.g., a laptop computer), and
`other devices (e.g., a personal digital assistant: PDA) having
`the combined functionality of both a mobile station and a
`mobile terminal, or having other terminal capabilities. Here
`inafter, an access terminal (AT) will be referred to as a
`“mobile” for the sake of brevity.
`In a conventional mobile communications system, a plu
`rality of mobiles (e.g., cellular phones, portable computers,
`etc.) are served by a network of base stations, which serve
`to allow the mobile stations to communicate with other
`components in the communications system. Various types of
`mobile communications systems are known, including Code
`Division Multiple Access (CDMA), time division multiple
`access (TDMA), frequency division multiple access
`(FDMA), and various enhancements and improvements
`thereto which are generally referred to as next generation
`mobile communications systems.
`CDMA is most widely accepted and continues to develop
`and evolve. In particular, CDMA technology evolution (such
`as the so-called “cdma2000' technology or other next gen
`eration CDMA systems) will provide integrated voice with
`simultaneous high-speed packet data, video and video con
`ferencing capabilities. Currently, the third generation (3G)
`evolution of cdma2000 1x wireless communications is being
`reviewed or partially adopted by certain standards bodies,
`such as 3GPP and 3GPP2 (The Third Generation Partnership
`Project 2).
`For example, a baseline framework for cdma2000 1xEV
`DV (1xEVolution Data and Voice) was recently reached by
`the 3GPP2. The 1xEV-DV Standard will be backward com
`patible with existing CDMA IS-95A/B and CDMA2000 1x
`systems, allowing various operators seamless evolution for
`their CDMA systems. Other types of systems that are
`evolving from CDMA include High Data Rate (HDR)
`technologies, 1xEvolution Data Only (1xEV-DO) tech
`nologies, and the like, which will be explained in more detail
`hereinafter.
`The present disclosure focuses on data transmission tech
`niques between base stations and mobiles. Thus, a detailed
`description of additional components, elements and process
`ing procedures (not specifically mentioned herein) have
`been omitted so that the features of the present invention are
`not obscured. One skilled in the art would have understood
`that various other components and techniques associated
`with base stations and mobiles already known in the art but
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
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`55
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`60
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`65
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`

`

`3
`represents intolerable latency within a voice channel. On the
`other hand, transfer of digital data packets is typically
`asymmetrical, with many more packets being sent from the
`base station to a particular mobile via a downlink (the
`forward link), than from the mobile to the base station via an
`uplink (the reverse link).
`In high speed data packet transfers, users appear to be
`tolerant of data transfer latencies or delays, with latencies of
`up to 10 seconds being encountered in current wireless data
`systems. While such delays appear to be tolerated by the
`user, the delays, attributable to relatively low effective data
`transfer rates, are undesirable. One proposed solution,
`known as “CDMA/HDR' (Code Division Multiple Access/
`High Data Rate), uses various techniques to measure chan
`nel data transfer rate, to carry out channel control, and to
`mitigate and Suppress channel interference.
`Conventional CDMA systems must handle both voice and
`data. To handle voice signals, the delay between the time
`that information is sent and the time that the information is
`received must be kept relatively short. However, certain
`communications systems used mostly for handling data
`packets can tolerate relatively longer delays or latencies
`between the time that information is sent and the time that
`the information is received. Such data handling communi
`25
`cations systems can be referred to as High Data Rate (HDR)
`systems. The following description will focus on HDR
`systems and techniques, but those skilled in the art would
`understand that various other mobile communications sys
`tems and techniques for handling high data rates, such as
`30
`1xEV-DO, 1xEV-DV, and the like, fall within the scope of
`the present disclosure.
`In general, a High Data Rate (HDR) system is an Internet
`protocol (IP) based system that is optimized for transmitting
`data packets having bursty characteristics and not sensitive
`to latencies or delays. In HDR systems, a base station is
`dedicated to communicating with only one mobile station at
`any one time. An HDR system employs particular tech
`niques allowing for high-speed data transfers. Also, HDR
`systems are exclusively used for high-speed data transfers
`40
`employing the same 1.25 MHz of spectrum used in current
`IS-95 systems.
`The forward link in an HDR system is characterized in
`that the users are not distinguished in terms of orthogonal
`spreading codes, but distinguished in terms of time slots,
`whereby one time slot can be 1.67 ms (milliseconds). Also,
`on the forward link of an HDR system, the mobile (access
`terminal AT) can receive data services from about at least
`38.4. Kbps to about at most 2.4576 Mbps. The reverse link
`of an HDR system is similar to the reverse link of an IS-95
`system, and employs a pilot signal to improve performance.
`Also, traditional IS-95 power control methods are used for
`providing data services from about 9.6 Kbps to about 153.6
`Kbps.
`In the HDR system, a base station (a part of the access
`network AN) can always transmit signals at its maximum
`transmission power, as virtually no power control is required
`because only one user occupies a single channel at a
`particular time resulting in practically no interference from
`other users. Also, in contrast to an IS-95 system requiring an
`equal data transfer rate for all users, an HDR system need
`not deliver packet data to all users at equal data transfer
`rates. Accordingly, users receiving high strength signals can
`receive services employing high data rates, while users
`receiving low strength signals can be accorded with more
`time slots so that their unequal (i.e., lower) data rate is
`compensated.
`
`4
`In conventional IS-95 systems, because various signals
`(including pilot signals) are simultaneously transmitted to all
`users, interference due to pilot signals and undesirably high
`power consumption are problematic. However, in HDR
`systems, pilot signals can be transmitted at maximum power
`because the so-called “burst' pilot signals are employed.
`Thus, signal strength can be measured more accurately, error
`rates can be reduced, and interference between pilot signals
`is minimized. Also, as the HDR system is a synchronous
`system, pilot signals in adjacent cells are simultaneously
`transmitted, and interference from pilot signals in adjacent
`cells can also be minimized.
`FIG. 1 shows a portion of a conventional reverse channel
`structure for sending transmission data rate increase infor
`mation from a base station to a mobile. A base station (not
`shown) approximates (or measures) a load on the reverse
`link, and prepares to send to a mobile (not shown) various
`messages indicating whether the reverse link load is large or
`small. A bit repetition means 10 repeats the bits in the
`messages to be sent a certain number of times to improve
`signal reliability.
`Thereafter, a signal point mapper 11 maps the signal from
`the bit repetition means 10 by, for example, changing all “0”
`bits to “+1 and all “1” bits to “-1 to allow further
`processing. The resulting signal is combined with a so-called
`“Walsh cover signal and transmitted over the Reverse
`Activity (RA) channel to the mobile.
`A conventional mobile receives the messages sent by the
`base station via the RA channel indicating that the current
`reverse link load is too large, and the mobile reduces the
`current packet data rate on the reverse link by one-half (1/2)
`so that the load on the reverse link is decreased.
`
`SUMMARY OF THE INVENTION
`
`Agist of the present invention involves the recognition by
`the present inventors of the drawbacks in the previously
`known art. In particular, previously known techniques (e.g.,
`mobile communications systems under the standards of
`IS-95, HDR, IMT-2000, etc.) for controlling data transmis
`sion rates between mobiles and a base station do not
`effectively consider the particular data transmission circum
`stances and channel conditions of each mobile station.
`Previously known HDR systems do not employ effective
`power control techniques, thus there are difficulties in pro
`viding high-speed data transmissions to those mobiles
`located far from the base station requiring signal transmis
`sions at a higher power compared with the signal transmis
`sions for mobiles located in proximity to the base station
`requiring only low level power.
`The previously known HDR system is disadvantageous in
`that, when the base station detects the load on the reverse
`link to be too large and feeds back this information via a
`reverse activity (RA) channel, the reverse link packet data
`rate is unconditionally reduced by one-half for all users
`(mobiles), and thus overall data throughput at each base
`station is undesirably reduced. The previously known art
`ignores the situations that individual mobiles have different
`requirements and should advantageously be controlled indi
`vidually in a dedicated manner.
`Additionally, the previously known HDR system is inef
`ficient because no messages are sent to the mobiles to
`indicate that their packet data rates should be increased
`when the reverse link load is small.
`Furthermore, the previously known art merely considers
`the reverse link load. However, in practical data packet
`transmission applications, the channel or link conditions,
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`Such as signal interference and transmission power require
`ments, and other communications environment factors effect
`data transmissions on the reverse link.
`To address at least the above-identified previously known
`art problems, the present invention utilizes information fed
`back from the forward link for data packet transmission over
`the reverse link upon considering the particular data trans
`mission circumstances and channel conditions of each
`mobile station and accordingly controlling the mobiles in a
`dedicated manner. By doing so, the data transmission rate
`over the reverse link is improved. More specifically, to
`improve reverse link data transmission rates, messages
`informing the mobile station to adjust (increase, decrease or
`maintain) its data transmission rate are sent from the base
`station in accordance with reverse link load information.
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`mining means can comprise the transmission data rate
`controller 23 and the transmission processor 24, in their
`entirety or portions thereof.
`Also, the mobile according to an embodiment of the
`present invention can comprise an adjusting means opera
`tively connected with the determining means, which adjusts
`a data transmission rate based upon a comparison result
`received from the base station in a dedicated manner via a
`common channel, the comparison result being obtained by
`comparing the transmission energy level and an interference
`level of signals sent to the base station by the mobile
`stations. Here, the adjusting means can comprise the trans
`mission data rate controller 23, and the transmission pro
`cessor 24, in their entirety or portions thereof.
`Furthermore, the mobile according to an embodiment of
`the present invention can comprise a transceiver operatively
`connected with the adjusting means, which transmits packet
`data on the reverse link in accordance with the adjusted data
`transmission rate. Here, the transceiver can comprise the
`reception processor 21, the demodulator 22, the transmission
`processor 24, and antennae A1 and A2, in their entirety or
`portions thereof.
`FIG. 3 shows a partial structure of a base station accord
`ing to an embodiment of the present invention. A base
`station 30 comprises a reception processor 31, an interfer
`ence level detector 32, a comparator 33, a determinator 34,
`and a transmission processor 35. The reception processor 31
`processes (e.g., demodulates) the signals received from
`mobiles (not shown) via a reception antenna A3. The inter
`ference level detector 32 receives the processed signals from
`the reception processor 31 for estimating and/or detecting a
`level of signal interference related to the processed signals.
`As understood by those skilled in the art, there are various
`types of signal interference between mobiles and base
`stations in mobile communications. For example, in the case
`of the reverse link, an important parameter is the rise in the
`level of the total amount of noise over the level of the
`thermal noise at a base station. This parameter is referred to
`as the “rise over thermal (ROT). The rise over thermal
`(ROT) corresponds to the loading of the reverse link.
`Typically, a communications system attempts to maintain
`the ROT near a predetermined value. If the ROT is too great,
`the range of the cell is reduced and the reverse link is less
`stable. A large ROT can also cause Small changes in instan
`taneous loading that result in large excursions in the output
`power of the mobile station. When the ROT is considered to
`be too high (e.g., above a desired threshold level), the data
`transmission rate can be decreased or even interrupted until
`the reverse link is stabilized. In contrast, a low ROT can
`indicate that the reverse link is not heavily loaded, thus
`potentially wasting available capacity. Thus, if the ROT is
`considered to be too low (e.g., below a desired threshold
`level), the data transmission rate can be advantageously
`increased. It will be understood by those skilled in the art
`that methods other than measuring the ROT can be used in
`determining the loading of the reverse link.
`After the interference level detector 32 detects the signal
`interference, the comparator 33 compares the detected level
`of signal interference with a threshold value in order to
`estimate (determine) the load on the reverse link. The
`determinator 34 determines a transmission data rate adjust
`information (e.g., increase, decrease or maintain) based on
`the reverse link load determined by the comparator 33, and
`determines a position of each mobile (i.e., a physical loca
`tion of each mobile in the cell/sector served by the base
`station) based on the rate control bit (RCB) position in the
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 shows a portion of a conventional reverse channel
`structure for sending transmission data rate increase infor
`mation from a base station to a mobile;
`FIG. 2 shows a partial structure of a mobile according to
`an embodiment of the present invention;
`FIG. 3 shows a partial structure of a base station accord
`ing to an embodiment of the present invention;
`FIG. 4 shows the details of certain relative portions of the
`determinator 34 in a base station, a portion of which is
`shown in FIG. 3;
`FIG. 5 is a flow chart showing the main steps involved in
`transmitting transmission data rate adjust information to
`each mobile in a 1xEV-DV or 1xEV-DO system according
`to the present invention;
`FIG. 6 is a flow diagram of the method for controlling the
`data transmission rate in accordance with the present inven
`tion;
`FIG. 7 is a flow diagram of embodiment according to the
`present invention;
`FIG. 8 shows the updating procedure of the BS RCV
`according to the present invention;
`FIG. 9 shows the procedures for generating rate control
`information using the BS RCV values according to the
`present invention; and
`FIG. 10 shows an example of how the reverse link data
`rate is controlled using the BS RCV values according to the
`present invention.
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`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`
`FIG. 2 shows a partial structure of a mobile according to
`an embodiment of the present invention. A mobile 20
`comprises a reception processor 21, a demodulator 22, a
`transmission data rate controller 23, and a transmission
`processor 24. The reception processor 21 processes the
`signals received from a base station via a reception antenna
`A1. The demodulator 22 demodulates the signals processed
`by the reception processor 21. The transmission data rate
`controller 23 controls the transmission data rate based on the
`transmission data rate adjustment information in the signals
`processed by the demodulator 22. The transmission proces
`Sor 24 transmits signals via a transmission antenna A2 to the
`base station in accordance with the control of the transmis
`sion data rate controller 23.
`According to FIG. 2, the mobile according to an embodi
`ment of the present invention can comprise a determining
`means which determines a transmission energy level
`required for transmitting to a base station. Here, the deter
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`channel slots. The RCB position in the channel slots allows
`mobiles to be discriminated from one another.
`The transmission processor 35 modulates a transmission
`signal for sending the transmission data rate adjust infor
`mation from the determinator 34 to each mobile, and trans
`mits signals to each mobile via a transmission antenna A4.
`Here, the signals including the RCB information are trans
`mitted to each mobile via a common channel. The common
`channel can be a known channel already used in conven
`tional mobile communications. For example, the so-called
`“RA channel can be employed in the present invention for
`transmitting signals and RCB information to each mobile.
`Alternatively, the signals including the RCB information are
`transmitted to each mobile via a newly established channel
`(Common Reverse Packet Data Control Channel—CRPD
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`CCH), not currently existing in conventional mobile com
`munications systems and techniques. Here, various conven
`tional techniques may be employed in establishing a new
`type of channel, with a feature of the present invention being
`the use of rate control bit (RCB) in the frames (16 slots)
`transmitted to the mobiles.
`According to FIG. 3, a base station according to an
`embodiment of the present invention can comprise a deter
`mining means, which determines an interference level of
`signals received from the mobile stations, and determines a
`transmission energy level required for each mobile station.
`Here, the determining means can comprise the interference
`level detector 32 and the comparator 33, in their entirety or
`portions thereof.
`Also, a base station according to an embodiment of the
`present invention can comprise a comparing means opera
`tively connected with the determining means, which com
`pares the interference level with the transmission energy
`level to obtain a comparison result for each mobile station.
`Here, the comparing means can comprise the comparator 33
`and determinator 34, in their entirety or portions thereof.
`Additionally, a base station according to an embodiment
`of the present invention can comprise a transceiver opera
`tively connected with the comparing means, which sends the
`comparison result via a common channel on a forward link
`to each mobile station in a dedicated manner in accordance
`with the comparing, and receives packet data on the reverse
`link in response to the sending. Here, the transceiver can
`comprise a reception processor 31, transmission processor
`35, and antennae A3 and A4, in their entirety or portions
`thereof.
`Accordingly, by using the general features of a mobile
`shown in FIG. 2 and the features of a base station shown in
`FIG. 3, data packets can be transmitted between the mobile
`and base station in accordance with the present invention. A
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